1. Field of the Invention
The invention concerns an outflow channel for the transfer and conditioning of molten glass from a glass melting and refining zone supplied with vitrifiable materials to a flat-glass forming zone. Such a channel is more particularly incorporated into the structure of devices commonly known as melting furnaces which are designed for the continuous supply of molten glass to flat-glass forming installations based on the float-glass process.
2. Background of the Related Art
In order to melt the vitrifiable materials and condition the molten glass so that it displays the requisite quality, and particularly good chemical and thermal homogeneity, such furnaces are provided with successive compartments discharging to one another, each having well defined functions.
There is know from EP-8-0 304 371 a furnace comprising a first compartment in which is effected the melting of the vitrifiable materials, which compartment is followed by another forming a neck, known as a corset and discharging to a compartment known as a conditioning compartment, where the glass is conditioned. This compartment then delivers the homogenized glass to an outflow channel, the function of which is limited to transferring the glass to the forming installation.
Such type of furnace, while making it possible to supply a glass of high quality, is not devoid of certain disadvantages. For example, its structure is not of very simple design since it involves no less than four separate compartments of very different dimensions. Moreover, the so-called conditioning compartment where conditioning of the glass takes place is designed in such a way as to be able to generate at will a belt of convective recirculation of the glass in the melting compartment, that is, a so-called "return" current. While this recirculation current is useful optimizing the conditioning of the glass by increasing its dwell time in the furnace, it requires considerable heating of the melting compartment where the glass recirculates continuously at the lower temperature obtained from the conditioning compartment.
There is furthermore known from patent U.S. Pat. No. 3,294,512 a furnace, the melting compartment of which discharges to a compartment which ensures both transfer and conditioning of the glass, and the dimensions of which define a sufficiently restricted depth of glass to prevent the formation of a convective current of glass. However, the conditioning of the glass in this manner may not be sufficient. This furnace is nevertheless designed in such a way as to promote the generation of convective currents within the glass but in the melting compartment in the vicinity of the junction with the conditioning compartment.